1. Field of the Invention
Embodiments of the present invention relate generally to a heat exchanger having tube-and-fin assemblies, such as found in a diesel engine cooling system, and more particularly to a support for the tube-and-fin assemblies such that alignment of the tubes and the overall strength and rigidity of the heat exchanger is enhanced.
2. Description of Related Art
A heat exchanger includes a multiplicity of tube-and-fin assemblies. The tube-and-fin assemblies are mounted in headers, arranged in columns and rows, and interconnected to receive and pass a heating/cooling fluid (dependent upon application). These tube-and-fin assemblies may be of the removable type or soldered in place. In certain environments, the tube-and-fin assemblies must have considerable length in order to provide sufficient heat transfer. The rigidity of the assembly decreases with increased length, and thus it is often necessary in such applications to include a central header, in essence splitting the tube-and-fin assemblies in half. Utilization of a central header does, however, substantially increase cost and reduce fin surface area, thereby requiring a larger heat exchanger to achieve a given heat transfer capacity.
Each tube-and fin assembly may be designed to be easily removable from the headers for repair and/or replacement. See for example FIG. 8 of U.S. Pat. No. 4,216,824. The tube-and-fin assemblies may also be soldered or otherwise secured in place. Typical tube-and-fin assemblies include a generally elliptical tube having flat or flattened sides and a pair of heat-dispensing fins secured along the flat sides of the tube. In such a design, the fin elements may be individually attached to the flow tube or they may be in the form of a corrugated fin strip. The flow tube may extend beyond or be coextensive with the fin elements, or alternatively, the fin elements may extend beyond the flow tube. In another type of assembly, the tube configuration is substantially circular in cross section. As is well known in the art, the fluid passes through the tube and heat therefrom is dispensed by the fins into the environment. Examples of tube and fin element designs useful in the present invention are shown in U.S. Pat. Nos. 4,570,704; 4,344,478; 4,216,824; 3,391,732; 5,433,268; and 5,236,045 each of which are hereby incorporated by reference in its entirety for all purposes.
To ensure proper operation and sufficient heat transfer (e.g., cooling of the fluid in a radiator application and heating of the environment in a heat recovery application), it is desirable to maintain the spacing between tube-and-fin assemblies and to substantially control movement and/or vibration, without substantial forfeiture of fin surface area. Movement and vibration of the tube-and-fin assemblies, as a result of operation or impact, can produce serious damage due to (i) excessive movement or deflection of individual assemblies, or (ii) contact between adjacent assemblies. In addition, loss of fin surface area such as by removal of fins from the flow tube, renders the heat exchanger less effective for a particular application.
It is possible to essentially band together the rows and/or columns of tube-and-fin assemblies, whether the fins are of the corrugated fin or circular fin type, through use of a continuous strip of metal or other suitable material used to confine and support the tube-and-fin assembly and thereby increase the strength and rigidity of the heat exchanger. See FIG. 4 of U.S. Pat. No. 4,216,824. These types of continuous strip supports may also be designed to prevent movement of the strip along the length of the flow tube. The use of continuous strip supports, unfortunately, substantially inhibits the ready removal and repair or replacement of any single damaged tube-and-fin assembly. To avoid the repair problem, various individual xe2x80x9cspacersxe2x80x9d are now available. One such spacer is shown in U.S. Pat. No. 4,216,824 and is designed to be inserted between fin elements and is held in place by friction between the fin elements and the spacer. One difficulty with this spacer and others presently available is that, with vibration or separation of the fin from the flow tube, the spacer can dislodge or separate from the tube-and-fin assembly, thereby becoming ineffective. In addition, the spacer causes stress on solder joints between fin elements and the flow tube since the spacers rely on fin strength and solder joints to transfer stress or load encountered by a heat exchanger. Further, the presently available spacers do not provide sufficient support in applications involving long tube-and-fin assemblies (e.g., in excess of forty inches in a typical vertical radiator application) or severe duty (e.g., an earth moving vehicle) to eliminate the need for center headers.
Embodiments of the present invention relate generally to an improved support for use in connection with the tube-and-fin assemblies of a heat exchanger. Importantly, the support is an individual support and is designed to be removably fastened to each individual tube-and-fin assembly and to removably engage adjacent supports so as to maintain the tube spacing and to enhance the strength and rigidity of the overall heat exchanger assembly. A row of supports of the present invention is advantageously capable of transferring significant load or other stress upon the heat exchanger through the row of supports themselves, rather than through the tube-and-fin assemblies thereby avoiding detrimental effects to the tube-and-fin assemblies such as weakening of the solder joints between fin elements and a flow tube.
Since the supports of the present invention can be separately removed from adjoining supports in the heat exchanger core, they advantageously provide for removal of individual tube-and-fin assemblies when necessary. The supports are further designed to engage an individual tube-and-fin assembly in a wrap around fashion such that existing fin elements of a tube-and-fin assembly need not be removed prior to installation of the supports, as with certain prior art tube supports. In this manner, the supports may simply engage an existing tube-and-fin assembly without eliminating existing fin surface area for heat transfer capabilities.
The supports are further characterized in having an alignment probe which assists in the installation of individual supports into a series of tube-and-fin assemblies. The alignment probe further advantageously prevents the support from moving in an axial direction along the length of the tube-and-fin assembly. In addition, due to the wrap around nature of the supports, the supports of the present invention reduce stress on solder joints which may be used to fixedly mount fin elements to flow tubes thereby reducing possibility of solder joint failure.
In its simplest aspect, one embodiment of the present invention is directed to an integral, wrap-around individual support designed to frictionally engage a tube-and-fin assembly encompassing the fin elements at the front and side planes of the tube-and-fin assemblies by using front and side engagement surfaces. The support is advantageously designed to allow removal of individual tube-and-fin assemblies. An alignment extension is provided (1) which advantageously allows for proper spacing between rows of tube-and-fin assemblies of adjacent rows, (2) which advantageously allows for proper row to row alignment, i.e. in-line or staggered column configurations and (3) which advantageously provides additional support between adjacent rows of tube-and-fin assemblies. One embodiment of the individual support of the present invention also includes an alignment probe which frictionally engages adjacent fin elements to assist in installation of the support and also to prevent movement along the axial length of the tube-and-fin assembly. Advantageously, the supports are interconnecting or interlocking to maintain proper spacing between tube-and-fin assemblies in a given row, to prevent movement between adjacent tube-and-fin assemblies in a given row and to provide a force distribution system along the row as opposed to through the tube-and-fin assemblies themselves thereby reducing tensile stress on the solder joints. Any force executed upon the heat exchanger is thus spread and dissipated through the row of interconnected supports, substantially improving the strength and rigidity of the heat exchanger. In addition, the supports require no additional devices different from the supports themselves to interlock or otherwise secure the tube-and-fin assemblies at the edges of a particular heat exchanger.
It is thus an object of the present invention to provide an improved support for use with tube-and-fin assemblies of heat exchangers, where the support frictionally engages the outer surface area of tube-and-fin assembly. The tube-and-fin assemblies may be of the removable type. Another object is an improved support having interconnecting capacity to increase the strength and rigidity of the heat exchanger. A further object is an improved, interconnecting support which does not significantly reduce the fin surface area of an existing tube-and-fin assembly. A still further object of the present invention is an improved support which reduces or eliminates movement of the support in the axial direction along the length of the tube-and-fin assembly, and otherwise maintains its original position.
It is also an object of the present invention to provide an improved assembly support readily adaptable to various tube-and-fin configurations. It is a further object to provide an improved support for use with long tube-and-fin assemblies, so as to reduce or eliminate the need for a center header plate. Still another object is an improved assembly support which is readily removable and does not interfere with removal of individual tubes and whereby the individuality of the assemblies is maintained, thereby facilitating inspection, removal, repair, and replacement of individual tube-and-fin assemblies.
Other objects, features or advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.